1. Field of the Invention
The present invention relates to a composite nonwoven fabric for protective clothing (protective garment) and a production method thereof, and more particularly, relates to a composite nonwoven fabric that is suitably used as protective clothing such as ordinary work clothing and medical underwear and gown because of its excellent water vapor permeability, water resistance, strength such as tear strength and feeling, and a production method of such a composite nonwoven fabric.
2. Description of the Prior Art
There is a recent tendency toward disposable protective clothing. In periodic overhaul works for machine and apparatus, for example, an ordinary work clothing is severely stained with dirt, etc., requiring a disposable work clothing. Also, in medical applications, a disposable medical clothing is needed for the protection against infections, etc.
The protective clothing used in these applications is required to have a water repellency and a bacteria-barrier property on its outer side exposed to the air and a sweat absorption on its inner side as well as a water vapor permeability for preventing stuffy feeling and an antistatic property as a whole.
Hitherto, the following products have been proposed as protective clothing and actually put on the market. However, these conventional protective clothing have some defects and, therefore, fail to fully satisfy the above requirements.
For example, there is known an ordinary work clothing made of a polyolefin nonwoven fabric produced by flash spinning. Such a work clothing is excellent in various barrier properties due to the polyolefin nonwoven fabric, but has a poor water vapor absorption, easily gives humid and stuffy feeling, and is uncomfortable under wear due to too a small thickness. A protective clothing using a hydroentangled nonwoven fabric made of a polyester fiber web/pulp sheet laminate, as proposed in Japanese Patent Application Laid-Open No. 59-94659, is also put on the market. The protective clothing is good in the feeling, but poor in the water repellency. Although the improvement of the water repellency is attempted by post treatments, the water pressure resistance is improved only to limited extent.
Further, a protective clothing made of a polyolefin-based spunlaid nonwoven fabric/meltblown nonwoven fabric/spunlaid nonwoven fabric composite, i.e., a composite nonwoven fabric represented by a so-called SMS, is also put on the market. However, this protective clothing has drawbacks such as poor feeling, stiff feeling and a low sweat absorption despite its low costs. To remove the drawbacks, Japanese Patent Application Laid-Open No. 10-96156 proposes a base fabric for disposable clothing which is produced by laminating spunlaid nonwoven fabrics made of aliphatic polyester on both surfaces of the meltblown nonwoven fabric. However, a disposable clothing made of such a base fabric is still insufficient in the water resistance and the bacteria-barrier property despite its improved hydrophilicity.
A clothing made of a composite fabric having a filter layer comprising a water vapor-permeable, water-resistant film, as proposed in Japanese Patent Application Laid-open No. 10-158909, is also put on the market. The proposed composite fabric has a low water vapor permeability to give humid and stuffy feeling and generates uncomfortable noise peculiar to the film. In addition, a protective clothing made of a composite comprising a filter layer and a nonwoven fabric is also put on the market. The filter layer is formed by making a thermoplastic elastomer resin into a hydrophilic film to impart the water vapor permeability. However, this protective clothing has an excessively high swelling property and a low shape stability despite its good water vapor permeability.